glibc/manual/examples/search.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

/* Define an array of critters to sort. */

struct critter
  {
    const char *name;
    const char *species;
  };

struct critter muppets[] =
  {
    {"Kermit", "frog"},
    {"Piggy", "pig"},
    {"Gonzo", "whatever"},
    {"Fozzie", "bear"},
    {"Sam", "eagle"},
    {"Robin", "frog"},
    {"Animal", "animal"},
    {"Camilla", "chicken"},
    {"Sweetums", "monster"},
    {"Dr. Strangepork", "pig"},
    {"Link Hogthrob", "pig"},
    {"Zoot", "human"},
    {"Dr. Bunsen Honeydew", "human"},
    {"Beaker", "human"},
    {"Swedish Chef", "human"}
  };

int count = sizeof (muppets) / sizeof (struct critter);



/* This is the comparison function used for sorting and searching. */

int 
critter_cmp (const struct critter *c1, const struct critter *c2)
{
  return strcmp (c1->name, c2->name);
}


/* Print information about a critter. */

void 
print_critter (const struct critter *c)
{
  printf ("%s, the %s\n", c->name, c->species);
}


/*@group*/
/* Do the lookup into the sorted array. */

void 
find_critter (const char *name)
{
  struct critter target, *result;
  target.name = name;
  result = bsearch (&target, muppets, count, sizeof (struct critter),
		    critter_cmp);
  if (result)
    print_critter (result);
  else
    printf ("Couldn't find %s.\n", name);
}
/*@end group*/

/* Main program. */

int
main (void)
{
  int i;

  for (i = 0; i < count; i++)
    print_critter (&muppets[i]);
  printf ("\n");

  qsort (muppets, count, sizeof (struct critter), critter_cmp);

  for (i = 0; i < count; i++)
    print_critter (&muppets[i]);
  printf ("\n");

  find_critter ("Kermit");
  find_critter ("Gonzo");
  find_critter ("Janice");

  return 0;
}